An object that is small in
comparison with other sizes
can be modelled as a particle.
This means the mass is
considered to be at a single
point. The fact it has no
dimensions means we can
ignore rotational effect as well
as wind resistance.
Rod
This is when an object has a small
dimesion in comparison with its other
dimensions like a metre ruler can be
modelled as a rod. This means the
mass is distributed along a staight
line.It has no thickness and does not
bend.
Lamina
When an object's
thickness is small in
comparison to its length
and width we model it as
a lamina. This means it
has its mass is distributed
across the flat surface. It
has no thickness and is
two dimensional.
Uniform
Body
If an object is uniform then its
mass is distributed evenly across
the object. This means we can
consider the mass to be
concentrated around one single
point. This only works when an
object has the even distribution of
mass like a book. If you cut bits out
of the book then it is no longer
even so is modelled as a
non-uniform body.
Light
When an object has a
very low mass in
comparison with
others then we model
it as having no mass at
all.
Inextensible string
An inextensible
string cannot be
stretched in any
way.
Smooth Surface
A surface that does
not apply the force of
friction due to it being
smooth.
Rough
Surface
A surface that
does apply
the force of
friction due to
its roughness
Wire
A rigid thin length of
metal which is one
dimensional is a wire. It
can be either rough or
smooth.
Smooth Light pulley
A pulley that is both
smooth and light. (Check
other definitions)
Bead
A particle which
can be threaded
onto and move
freely along a
wire.
Peg
A support from which an
object can be suspended
from or on which an object
can rest. Dimensionless and
normally fixed. Can be
smooth or rough.
Air resistance
Objects moving through
air will experience air
resistance due to
friction. We ignore this
in M1
Wind
Unless
mentioned
ignore it
Gravity
The force of attraction to the Earth.
This is called gravity. It is modeled
as a constant and uniform as well
as using the notation g. The
acceleration due to gravity is
assumed to be 9.8 unless
otherwise stated on your exam
paper.